Fluid pressure producing device



y o. H FOWLER 2,248,426

' v FLUID. PRESSURE PRODUCING DEVICE I Filed July. 11, 1938- 2 Sheets-Sheet 1 INVENTOR.

7 0. H. FOWLER 2,248,426

' I FLUID PRESSURE PRODUCING DEVICE Filed July 11, 1938 2 Shets-Sheet 2 Patented July 8, 1941 FLUID PQIE SSURE PRODUCING DEVICE Owen H. Fowler, Detroit, Mich., assignor to Bydraulic Brake Company, Detroit, Micln, a cor notation of California Application July 11, 1938, Serial No. 218,650

8 Claims. 7 (01. 60-545) This invention relates to fluid pressure braking systems, and more particularly to fluid pres-- sure producing devices.

.An object of the invention is to provide a fluid pressure producing device operative to increase pressure without increasing the applied operating force.

Another object of the invention is to provide a fluid pressure producing device including a low pressure producing means and a high pressure producing means operative to 'accomplish a transition from low to high pressure upon attaining a predetermined movement of the low pressure producing means.

A further object of the invention is to provide a fluid pressure producing device including a low pressure producing means and a high pressure producing means operative to dis-associate the low pressure producing means upon eifecting a transition from low pressure to high pressure.

Fig. 1 is a diagrammatical illustration of a' fluid pressure braking system embodying the invention;

Fig. 2 is a vertical sectional view of the fluid pressure producing device having associated therewith the reservoir shown partly in elevation and partly broken away;

Fig. 3 is a vertical sectional view illustrating the fluid pressure device on its compression stroke; l i

Fig. 4 is a sectional view substantially on line 4-4, Fig. 2; and

Fig. 5 is a vertical sectional view illustrating a modification of the fluid pressure producing device.

Referring to the drawings for more specific details of the invention, I0 represents a fluid pressure producing device including a cylinder I2 adapted to be mounted in a fixed position. The cylinder has one end. open, and its other end closed as by a head l4 provided with-an exhaust port l6 controlled by a two-way valve i8. The open end of the cylinder has rigidly secured thereto a head provided with a concentric orifice 22, and arranged in the wall of the cylinder are spaced ports 24 and 26 known in the art,

respectively, as a supply port and a compensating port. The head 20 has a greater diameter than the diameter of the cylinder, hence the head'has a portion overhanging the cylinder. A

sealing cup 28 seated on the head has a concenconjunction with the Wall of the cylinder an annular chamber 38, and a skirt 40 having a concentric recess 42 extended well into the. body of the piston. A plurality of spaced passages 44 arranged in the body adjacent the skirt provide communications between the annular chamber 38 and the recess 42, and a plurality of spaced passages 46 in the head of the piston provide communications between the annular chamber 38 and, that portion'of the cylinder forward of the piston.

A sealing cup 48 on the head of the piston 32 controls the passages 46, and a spring 50 interposed between the sealing cup 48 and the twoway valve i8 serves to retain the cup and valve against displacement and also to return the piston to its retracted position.

A cylinder 52reciprocable on the fixed cylinder i2 has one end closed as by a head 54 and its other end open; The head 54 has suitably mounted therein a thrust pin 56 extended into the cylinder with its free end in the recess 42 of the piston 32. The head of the thrust pin has a recess 58, the purpose of whichwill hereinafter appear, and a spring 60 interposed be,- tween the head 54 and the sealing cup '28 serves to retain the cupagainst displacement. and also to return the cylinder52 to itsretracted position. a

In the wall of the cylinder 52 is a supply port 62 communicating with a suitabie'reservcir 64 mounted on the cylinder. This supply port is arranged immediately forward of the sealing cup 28 and is adapted to be closed by the-cup upon the initial movement of the cylinder 52 on its compression stroke. The open end ofthe 'cylinder52 extends over the cylinder l2 beyond the ports 24 and 26, and is closed by a ring 66 so as to provide an'annular chamber 68 communieating with the cylinder [2 byway of the ports 24 and 26. The ring 66 is suitablysecured to the open 'end of the cylinder 52 and sl-idably embraces the cylinder I2. A sealing cup 1'9 seated on the ring-66 inhibits seepage offluid from the chamber 68, and a spring 12 interposed between the sealing cup 10. and the sealing cup 30 seated on the overhanging portion of the head 20 retains these cups in position and also determines the retracted position of the cylinder 52 wherein the cylinder 52 is balanced between the springs 80 and I2. The cylinder 52 also has in its wall a port I4 communicating with the annular chamber 68 and normally closed as by a bleeder screw 16.

A fluid pressure delivery pipe or conduit I8 connected to'the discharge port I6 of the cylinder I2 has branches connected respectively to fluid pressure actuated motors 80, preferably arranged in pairs, one pair for actuating the brakes associated with the front wheels of the vehicle, and another pair for actuating the brakes associated with the rear wheels of the vehicle.

The brakes, which may be of any desirable type, preferably include a fixed support or backing plate 82 adapted to be secured to an axle or to an axle housing, a rotatable drum 84 associ-' ated with the backing plate adapted to be secured to a wheel, a pair of friction elements or shoes 06 pivoted on the backing plate for cooperation with the drum, a retractile spring 88 connecting the shoes, and a motor corresponding to the motors 80 mounted on the backing plate between the shoes and operative to actuate the shoes into engagement with the drum against the resistance of the retractile spring.

The socket 58 in the head of the thrust pin.

providing the communication between the cylinder 52 and the reservoir 52, and thereafter as the cylinder 52 advances the fluid in the cylinder 52 is displaced therefrom through the orifice 22 in the head 20, the recess 42 and passages 44 in the reciprocable piston 32 into the annular chamber 38, thence through the passages 46 in the head of the reciprocable piston, past the sealing cup 43, into that portion of the fixed cylinder I2 forward of the reciprocable piston, thence past the two-way valve I0, through the discharge port I6 and fluid pressure pipe or conduit I8 and its respective branches into the fluid pressure actuated motors 80, causing energization of the motors and resulting in actuation of the shoes 86 into engagement with the drums 84 against the resistance of the retractile springs 88.

During this operation, the cylinder 52 has traveled suiiiciently to seat the thrust pin 56 in the recess 42 in the reciprocable piston 32, and thereafter, as the cylinder 52 advances, the reciprocable piston is moved on its compression stroke. During the initial movement of this piston on its compression stroke, the'cup 48 closes the port 26, whereupon the pressure on the fluid is transferred from the large cylinder 52 to the small cylinder I2, and thereafter the fluid in the large cylinder is displaced therefrom through the orifice 22 in the head 20, the recess 42 and passages in the reciprocable piston 32 into the annular chamber 30, thence through the port 24 into the annular chamber 58, thence through the port52 into the reservoir 54, and the fluid in the cylinder I2 forward of the reciprocable piston is displaced therefrom past the two-way valve I8, through the discharge port I and fluid pressure delivery pipe 18 and its respective branches into the fluid pressure actuated motors 80, causing further energization of the motors 00, resulting in further actuation of the shoes into engagement with the drums 84 against the resistance of the drums so as to eifectively retard rotation of the retractile springs.

Upon the conclusion of a braking operation, the foot pedal lever 94 is released and returns to its retracted position under the influence of the retractile spring 38. This results in release of the cylinder 52 and return thereof to its retracted position under the influence oi the spring 60 wherein the cylinder is balanced between the springs 60 and I2.

During this operation the reciprocable piston 32 is returned to its retracted position under the influence of the retractile spring 50, and as the piston 32 returns to its retracted position a partial vacuum is created in that portion of the cylinder I2 forward of the reciprocable piston 32. This results in drawing fluid from the reservoir through the port 52 into the cylinder 52, thence through the orifice 22 in the head 20, the recess 42 and passages 44 in the reciprocable piston 32 into the annular chamber 38, thence through the passages 46 in the head of tlie reciprocable piston,

past the sealing cup 48 into that portion of the cylinder I2, completely filling this cylinder.

concomitantly with this operation fluid is returning to the cylinder I2 from the fluid pressure actuated motors .80 and the fluid pressure delivery pipes connecting the motors to the cylinder I2. This results in the cylinder I2 receiving a. quantity of fluid in excess of its capacity, and this excess quantity of fluid is displaced from the cylinder I2, through the port 25, into the annular chamber 68, thence through the port 24 into the annular chamber 30, thence through passage 54, recess 42 in the reciprocable head and orifice 22 in the piston 20 into cylinder 52, thence by way of port 62 into the reservoir.

A modification of the fluid pressure producing device is illustrated in Fig. 5. In this embodiment of the invention a cylinder I02 adapted to be mounted in an upright position has its lower end closed as by a head I04 provided with a discharge port I08 controlled by a two-way valve I08. The upper end of the cylinder has secured thereto a head IIO provided with a concentric orifice I I2, and arranged in the wall of the cylin der are spaced ports H4 and H3. The head IIO has a greater diameter than the diameter of the cylinder so that the perimeter of the head overhangs the cylinder. A sealing cup II8 seated on the head. H0 hasa concentric opening registering with the orifice H2 in the head, and seated on the back of the overhanging portion of the head is a sealing cup I20. 7

A piston I22 reciprocable in the cylinder I02 seats on the back of the head H0; The piston I22 includes a head I24, a reduced body portion I26 providing in conjunction'with the cylinder an annular chamber I20, and a skirt I30 having a concentric recess I32 extending well into the body of the cylinder, and the body has a plurality of spaced passages I34 arranged therein adjacent the skirt providing communications between the annular passage I28 and the recess I32. The head of the piston I26 has a plurality of spaced passages I30 therethrough providing communications between the annular passage I28 and that portion of the cylinder I02 forward of the piston. A sealing cup I38 seated on the head of the piston I26 controls the passages I36, and a spring I40 embracing the cylinder I02.

interposed between the sealing cup I38 and the two-way valve I08 serves to retain the cup and valve against displacement and also to return the piston to its retracted, position.

A cylinder I42 reciprocable on the cylinder I02 has thereon a concentric reservoir I44 communicating with the cylinder as by way of a port I46 arranged in the wall of the cylinder immediately forward of the sealing cup II8 on the head 0. The cylinder I42 is closed at its upper end by a head I48 having mounted therein a thrust pin I50 extending downwardly into the recess I32 of the piston I22, and a spring I52 interposed between the head I46 and thesealing cup I I8 serves to retain the cup against displacement and also to return the cylinder 142 to its retracted position. The lower end of the cylinder is closed by a ring I54 suitably secured thereto and slidably The ring supports a sealing ,cup I56, and a spring I58 interposed between the sealing cup I56 and the sealing cup I20 serves to retain these cups against displacement and also to determine the retracted position of the cylinder I42.

Because of the increased diameter of the head I I0, the walls of the respective cylinders I02 and I42 are in spaced relation to one another. This provides, between the back of the head H and the ring I50, an annular chamber I60 communicating with the cylinder I02 by way of the ports H4 and H6.

The reservoir I44 is closed by a cover plate I62 having a plurality of spaced openings I64 for venting the reservoir to the atmosphere. The cover plate is held against displacement by a head I66 on the thrust pin I50, and the head I66 has a socket I68 for the reception of a thrust pin I10.

The operation of the fluid pressure producing device illustrated in the modification is identical to that of the preferred form of the invention. The only difference between the two devices is to be found in the structure of the reservoirs, one being adapted for mounting in substantially horizontal position, and the other adapted for mounting in substantially vertical position. Hence it is not deemed necessary to repeat the operation.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid pressure producing device comprising a small fixed cylinder, a large movable cylinder telescoping the small cylinder, a reservoir communicating with the largecylinder, a variable chamber between the peripheral walls of the cylinders continuously communicating with the small cylinder through its peripheral wall and adapted to communicate with the reservoir after a predetermined movement of the large cylinder, an orificed head on the inner end of the small cylinder, a reciprocable piston in the small cylinder, and means carried by the large cylinder for advancing the reciprocable piston.

2. A fluid pressure producing device comprising a small fixed cylinder, a relatively large movable cylinder telescoping the small cylinder, a r servoir communicating with the large cylinder, a chamber between the peripheral walls of the cylinders continuously communicating with the small cylinder through its peripheral wall and adapted to communicate with the reservoir after a predetermined movement of the large cylinder, an orificed head on the inner end of the small cylinder, a reciprocable piston in the small cylin der, means for by-passing fluid past the reciprocable piston, and means carried by the large cylinder for advancing the reciprocable piston.

3. A fluid pressure producing device comprising a small cylinder closed at one end by a head having a discharge port and open at its other end, an orificed head on the open end having a larger diameter than that of the cylinder, a reciprocable piston in the small cylinder, a relatively large cylinder closed at one end and open at its other end telescoping the small cylinder and providing in conjunction therewith a variable chamber communicating with the small cylinder, a ring on the open end of the large cylinder slidably embracing the small cylinder and providing a closure for the variable chamber, and a'pin in the head of the large cylinder extended through the orificed head and adapted to engage the reciprocable piston.

4. A fluid pressure producing device comprising a small cylinder closed at one end by a head having a discharge port and open at its other end, an orificed head on the open end, a reciprocable piston in the cylinder, a relatively large cylinder closed at one end and open at its other end telescoping the small cylinder and reciprocable on the orificed head, a ring on-the open end of the large cylinder slidably embracing the small cylinder,

a reservoir communicating with the large cylinder forward of the orificed head, means for balancing the large cylinder on the orificed head, and a thrust pin carried by the large cylinder for advancing the reciprocable piston.

5. A fluid pressure producing device comprising a small cylinder closed at one end by a head having a discharge port and open at its other end, an orificed head on the open end, a reciprocable piston in thecylinder normally seated on the back of the orificed head, a. relatively large cylinder closed at one end and open at its other end reciprocable on the orificed head, a reservoir coming a small cylinder closed at one end by a head having a discharge port and open at its other end, an orificed head on the open end having a diameter greater than the diameter of the small cylinder, a reciprocable piston in the small cylinder, means for by-passing fluid past the reciprocable piston, a relatively large cylinder reciprocable on the orificed head having one end closed and its other end open, a reservoir communicating with the large cylinder forward of the orificed head, a ring on the open end of the large cylinder slidably embracing the small cylinder and providing a closure for the large cylinder, a variable chamber between the cylinders communicating with the small cylinder and adapted to communicate with the reservoir after a predetermined movement of the large cylinder,

means for balancing the large cylinder on the orificed head, and a thrust pin on the head of the large cylinder extending through the oriflced head and adapted to engage and advance the reciprocable piston after a predetermined movement of the large cylinder.

7. A fluid pressure producing device comprising a small cylinder closed at one'end by a head having a discharge port and open at its other end, means for mounting the small cylinder in a fixed position, a two-way valve controlling the discharge port, an orificed head on the open end of the small cylinder having a diameter greater than the small cylinder, a reciprocable piston in the small cylinder, means for by-passing fluid past the reciprocable piston, a sealing cup on the reciprocable piston, a spring interposed between the sealing cup and the two-way valve urging the reciprocable piston to seaton the back of the oriflced head, a relatively large cylinder reciprocable on the orificed head having one end closed by a head and its other end open, a sealing cup on the orificed head, a spring interposed between the cup on the orificed head and the head of the large cylinder, a reservoir communicating with the large cylinder immediately forward of the sealing cup on the oriflced head, a ring on the open end of the large cylinder slidably embracing the small cylinder, a sealing cup on the ring, a sealing cup on the back of the oriflced head and a spring interposed between the cups, a variable chamber between the cylinders communicating with the small cylinder and adapted to communicate with the reservoir after a predetermined movement 01 the large cylinder, and a thrust pin on the head of the large cylinder extended through the orificed head and adapted to engage and advance the reciprocable piston.

8. A fluid pressure producing device comprising telescopic cylinders-closed at their outer ends and open at their inner ends, the closed end of the inner cylinder having a discharge port, an orificed head on the open end of the inner cylinder, a-rlng on the open end of the outer cylinder slidably embracing the inner cylinder, a reservoir communicating with the outer cylinder forward of the orificed head, a variable chamber between the cylinders back of the oriflced head communi cating with the small cylinder and adapted to communicate with the reservoir after a predetermined movement of the outer cylinder, a piston reciprocable in the inner cylinder, means for bypassing fiuid past the reciprocable piston, and means carried by the large cylinder for advancing the reciprocable piston.

OWEN H. FOWLER. 

